It is generally better to clone plants with really good genes and harvest the rest. If you are interested in cross breeding to get the most out of your growing setup, keep a few decent ones for crossbreeding. This is not my video, but it is a great tutorial for crossbreeding the perfect strain (all G's and Y's, though you could also go for H's if you live in the snow): https://youtu.be/I5w0KAqkHYI